//
// Community.CsharpSqlite.SQLiteClient.SqliteCommandBuilder.cs
//
// Author(s): Tim Coleman (tim@timcoleman.com)
//            Marek Habersack (grendello@gmail.com)
//
// Copyright (C) Tim Coleman, 2002
// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
// Copyright (C) 2007 Marek Habersack
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Data;
using System.Data.Common;
using System.Text;

namespace Community.CsharpSqlite.SQLiteClient
{
	public sealed class SqliteCommandBuilder : DbCommandBuilder
	{
		static readonly string clause1 = "({0} = 1 AND {1} IS NULL)";
		static readonly string clause2 = "({0} = {1})";

		DataTable _schemaTable;
		SqliteDataAdapter _dataAdapter;
		SqliteCommand _insertCommand;
		SqliteCommand _updateCommand;
		SqliteCommand _deleteCommand;
		bool _disposed;
		string _quotePrefix = "'";
		string _quoteSuffix = "'";
		string _tableName;
		SqliteRowUpdatingEventHandler rowUpdatingHandler;
		
		public new DbDataAdapter DataAdapter {
			get { return _dataAdapter; }
			set {
				if (_dataAdapter != null)
					_dataAdapter.RowUpdating -= new SqliteRowUpdatingEventHandler (RowUpdatingHandler);
				_dataAdapter = value as SqliteDataAdapter;
				if (_dataAdapter != null)
					_dataAdapter.RowUpdating += new SqliteRowUpdatingEventHandler (RowUpdatingHandler);
			}
		}

		public override string QuotePrefix {
			get { return _quotePrefix; }
			
			set {
				if (_schemaTable != null)
					throw new InvalidOperationException ("The QuotePrefix and QuoteSuffix properties cannot be changed once an Insert, Update or Delete commands have been generated.");
				_quotePrefix = value;
			}
		}

		public override string QuoteSuffix {
			get { return _quoteSuffix; }
			
			set {
				if (_schemaTable != null)
					throw new InvalidOperationException ("The QuotePrefix and QuoteSuffix properties cannot be changed once an Insert, Update or Delete commands have been generated.");
				_quoteSuffix = value;
			}
		}

		private SqliteCommand SourceCommand {
			get  {
				if (_dataAdapter != null)
					return _dataAdapter.SelectCommand as SqliteCommand;
				return null;
			}
		}

		private string QuotedTableName {
			get { return GetQuotedString (_tableName); }
		}

		public new SqliteCommand GetDeleteCommand ()
		{
			BuildCache (true);
			if (_deleteCommand == null)
				return CreateDeleteCommand (false);
			return _deleteCommand;
		}

		public new SqliteCommand GetInsertCommand ()
		{
			BuildCache (true);
			if (_insertCommand == null)
				return CreateInsertCommand (false);
			return _insertCommand;
		}

		public new SqliteCommand GetUpdateCommand ()
		{
			BuildCache (true);
			if (_updateCommand == null)
				return CreateUpdateCommand (false);
			return _updateCommand;
		}

		public override void RefreshSchema () 
		{
			// FIXME: "Figure out what else needs to be cleaned up when we refresh."
			_tableName = String.Empty;
			_schemaTable = null;
			CreateNewCommand (ref _deleteCommand);
			CreateNewCommand (ref _updateCommand);
			CreateNewCommand (ref _insertCommand);
		}

		protected override void SetRowUpdatingHandler (DbDataAdapter adapter)
		{
			if (!(adapter is SqliteDataAdapter)) {
				throw new InvalidOperationException ("Adapter needs to be a SqliteDataAdapter");
			}
			rowUpdatingHandler = new SqliteRowUpdatingEventHandler (RowUpdatingHandler);
			((SqliteDataAdapter) adapter).RowUpdating += rowUpdatingHandler;
		}
		
		protected override void ApplyParameterInfo (DbParameter dbParameter,
							    DataRow row,
							    StatementType statementType,
							    bool whereClause)
		{
			// Nothing to do here
		}

		protected override string GetParameterName (int position)
		{
			return String.Format ("?p{0}", position);
		}

		protected override string GetParameterName (string parameterName)
		{
			if (String.IsNullOrEmpty (parameterName))
				throw new ArgumentException ("parameterName cannot be null or empty");
			if (parameterName [0] == '?')
				return parameterName;
			return String.Format ("?{0}", parameterName);
		}
		

		protected override string GetParameterPlaceholder (int position)
		{
			return String.Format ("?p{0}", position);
		}
		
		protected override void Dispose (bool disposing)
		{
			if (!_disposed) {
				if (disposing) {
					if (_insertCommand != null)
						_insertCommand.Dispose ();
					if (_deleteCommand != null)
						_deleteCommand.Dispose ();
					if (_updateCommand != null)
						_updateCommand.Dispose ();
					if (_schemaTable != null)
						_schemaTable.Dispose ();
				}
				_disposed = true;
			}
		}

		private void BuildCache (bool closeConnection)
		{
			SqliteCommand sourceCommand = SourceCommand;
			if (sourceCommand == null)
				throw new InvalidOperationException ("The DataAdapter.SelectCommand property needs to be initialized.");
			SqliteConnection connection = sourceCommand.Connection as SqliteConnection;
			if (connection == null)
				throw new InvalidOperationException ("The DataAdapter.SelectCommand.Connection property needs to be initialized.");
				
			if (_schemaTable == null) {
				if (connection.State == ConnectionState.Open)
					closeConnection = false;	
				else
					connection.Open ();
	
				SqliteDataReader reader = sourceCommand.ExecuteReader (CommandBehavior.SchemaOnly |
										       CommandBehavior.KeyInfo);
				_schemaTable = reader.GetSchemaTable ();
				reader.Close ();
				if (closeConnection)
					connection.Close ();    
				BuildInformation (_schemaTable);
			}
		}

		private void BuildInformation (DataTable schemaTable)
		{
			_tableName = String.Empty;
			foreach (DataRow schemaRow in schemaTable.Rows) {
				if (schemaRow.IsNull ("BaseTableName") ||
				    (string) schemaRow ["BaseTableName"] == String.Empty)
					continue;

				if (_tableName == String.Empty) 
					_tableName = (string) schemaRow ["BaseTableName"];
				else if (_tableName != (string) schemaRow["BaseTableName"])
					throw new InvalidOperationException ("Dynamic SQL generation is not supported against multiple base tables.");
			}
			if (_tableName == String.Empty)
				throw new InvalidOperationException ("Dynamic SQL generation is not supported with no base table.");
			_schemaTable = schemaTable;
		}

		private SqliteCommand CreateInsertCommand (bool option)
		{
			if (QuotedTableName == String.Empty)
				return null;

			CreateNewCommand (ref _insertCommand);

			string command = String.Format ("INSERT INTO {0}", QuotedTableName);
			string sql;
			StringBuilder columns = new StringBuilder ();
			StringBuilder values = new StringBuilder ();

			int parmIndex = 1;
			foreach (DataRow schemaRow in _schemaTable.Rows) {
				if (!IncludedInInsert (schemaRow))
					continue;

				if (parmIndex > 1) {
					columns.Append (", ");
					values.Append (", ");
				}

				SqliteParameter parameter = null;
				if (option) {
					parameter = _insertCommand.Parameters.Add (CreateParameter (schemaRow));
				} else {
					parameter = _insertCommand.Parameters.Add (CreateParameter (parmIndex++, schemaRow));
				}
				parameter.SourceVersion = DataRowVersion.Current;
				columns.Append (GetQuotedString (parameter.SourceColumn));
				values.Append (parameter.ParameterName);
			}

			sql = String.Format ("{0} ({1}) VALUES ({2})", command, columns.ToString (), values.ToString ());
			_insertCommand.CommandText = sql;
			return _insertCommand;
		}
		
		private SqliteCommand CreateDeleteCommand (bool option)
		{
			// If no table was found, then we can't do an delete
			if (QuotedTableName == String.Empty)
				return null;

			CreateNewCommand (ref _deleteCommand);

			string command = String.Format ("DELETE FROM {0}", QuotedTableName);
			StringBuilder whereClause = new StringBuilder ();
			bool keyFound = false;
			int parmIndex = 1;

			foreach (DataRow schemaRow in _schemaTable.Rows) {
				if ((bool)schemaRow["IsExpression"] == true)
					continue;
				if (!IncludedInWhereClause (schemaRow)) 
					continue;

				if (whereClause.Length > 0) 
					whereClause.Append (" AND ");

				bool isKey = (bool) schemaRow ["IsKey"];
				SqliteParameter parameter = null;

				if (isKey)
					keyFound = true;

				bool allowNull = (bool) schemaRow ["AllowDBNull"];
				if (!isKey && allowNull) {
					if (option) {
						parameter = _deleteCommand.Parameters.Add (
							String.Format ("@{0}", schemaRow ["BaseColumnName"]), DbType.Int32);
					} else {
						parameter = _deleteCommand.Parameters.Add (
							String.Format ("@p{0}", parmIndex++), DbType.Int32);
					}
					String sourceColumnName = (string) schemaRow ["BaseColumnName"];
					parameter.Value = 1;

					whereClause.Append ("(");
					whereClause.Append (String.Format (clause1, parameter.ParameterName, 
									   GetQuotedString (sourceColumnName)));
					whereClause.Append (" OR ");
				}

				if (option) {
					parameter = _deleteCommand.Parameters.Add (CreateParameter (schemaRow));
				} else {
					parameter = _deleteCommand.Parameters.Add (CreateParameter (parmIndex++, schemaRow));
				}
				parameter.SourceVersion = DataRowVersion.Original;

				whereClause.Append (String.Format (clause2, GetQuotedString (parameter.SourceColumn),
								   parameter.ParameterName));

				if (!isKey && allowNull)
					whereClause.Append (")");
			}
			if (!keyFound)
				throw new InvalidOperationException ("Dynamic SQL generation for the DeleteCommand is not supported against a SelectCommand that does not return any key column information.");

			string sql = String.Format ("{0} WHERE ({1})", command, whereClause.ToString ());
			_deleteCommand.CommandText = sql;
			return _deleteCommand;
		}

		private SqliteCommand CreateUpdateCommand (bool option)
		{
			if (QuotedTableName == String.Empty)
				return null;

			CreateNewCommand (ref _updateCommand);

			string command = String.Format ("UPDATE {0} SET ", QuotedTableName);
			StringBuilder columns = new StringBuilder ();
			StringBuilder whereClause = new StringBuilder ();
			int parmIndex = 1;
			bool keyFound = false;

			foreach (DataRow schemaRow in _schemaTable.Rows) {
				if (!IncludedInUpdate (schemaRow))
					continue;
				if (columns.Length > 0) 
					columns.Append (", ");

				SqliteParameter parameter = null;
				if (option) {
					parameter = _updateCommand.Parameters.Add (CreateParameter (schemaRow));
				} else {
					parameter = _updateCommand.Parameters.Add (CreateParameter (parmIndex++, schemaRow));
				}
				parameter.SourceVersion = DataRowVersion.Current;

				columns.Append (String.Format ("{0} = {1}", GetQuotedString (parameter.SourceColumn),
							       parameter.ParameterName));
			}

			foreach (DataRow schemaRow in _schemaTable.Rows) {
				if ((bool)schemaRow["IsExpression"] == true)
					continue;

				if (!IncludedInWhereClause (schemaRow)) 
					continue;

				if (whereClause.Length > 0) 
					whereClause.Append (" AND ");

				bool isKey = (bool) schemaRow ["IsKey"];
				SqliteParameter parameter = null;

				if (isKey)
					keyFound = true;

				bool allowNull = (bool) schemaRow ["AllowDBNull"];
				if (!isKey && allowNull) {
					if (option) {
						parameter = _updateCommand.Parameters.Add (
							String.Format ("@{0}", schemaRow ["BaseColumnName"]), SqlDbType.Int);
					} else {
						parameter = _updateCommand.Parameters.Add (
							String.Format ("@p{0}", parmIndex++), SqlDbType.Int);
					}
					parameter.Value = 1;
					whereClause.Append ("(");
					whereClause.Append (String.Format (clause1, parameter.ParameterName,
									   GetQuotedString ((string) schemaRow ["BaseColumnName"])));
					whereClause.Append (" OR ");
				}

				if (option) {
					parameter = _updateCommand.Parameters.Add (CreateParameter (schemaRow));
				} else {
					parameter = _updateCommand.Parameters.Add (CreateParameter (parmIndex++, schemaRow));
				}
				parameter.SourceVersion = DataRowVersion.Original;
				whereClause.Append (String.Format (clause2, GetQuotedString (parameter.SourceColumn),
								   parameter.ParameterName));

				if (!isKey && allowNull)
					whereClause.Append (")");
			}
			if (!keyFound)
				throw new InvalidOperationException ("Dynamic SQL generation for the UpdateCommand is not supported against a SelectCommand that does not return any key column information.");

			string sql = String.Format ("{0}{1} WHERE ({2})", command, columns.ToString (), whereClause.ToString ());
			_updateCommand.CommandText = sql;
			return _updateCommand;
		}
		
		private void CreateNewCommand (ref SqliteCommand command)
		{
			SqliteCommand sourceCommand = SourceCommand;
			if (command == null) {
				command = sourceCommand.Connection.CreateCommand () as SqliteCommand;
				command.CommandTimeout = sourceCommand.CommandTimeout;
				command.Transaction = sourceCommand.Transaction;
			}
			command.CommandType = CommandType.Text;
			command.UpdatedRowSource = UpdateRowSource.None;
			command.Parameters.Clear ();
		}
		
		private bool IncludedInWhereClause (DataRow schemaRow)
		{
			if ((bool) schemaRow ["IsLong"])
				return false;
			return true;
		}

		private bool IncludedInInsert (DataRow schemaRow)
		{
			// not all of the below are supported by Sqlite, but we leave them here anyway, since some day Sqlite may
			// support some of them.
			if (!schemaRow.IsNull ("IsAutoIncrement") && (bool) schemaRow ["IsAutoIncrement"])
				return false;
			if (!schemaRow.IsNull ("IsHidden") && (bool) schemaRow ["IsHidden"])
				return false;
			if (!schemaRow.IsNull ("IsExpression") && (bool) schemaRow ["IsExpression"])
				return false;
			if (!schemaRow.IsNull ("IsRowVersion") && (bool) schemaRow ["IsRowVersion"])
				return false;
			if (!schemaRow.IsNull ("IsReadOnly") && (bool) schemaRow ["IsReadOnly"])
				return false;
			return true;
		}

		private bool IncludedInUpdate (DataRow schemaRow)
		{
			// not all of the below are supported by Sqlite, but we leave them here anyway, since some day Sqlite may
			// support some of them.
			if (!schemaRow.IsNull ("IsAutoIncrement") && (bool) schemaRow ["IsAutoIncrement"])
				return false;
			if (!schemaRow.IsNull ("IsHidden") && (bool) schemaRow ["IsHidden"])
				return false;
			if (!schemaRow.IsNull ("IsRowVersion") && (bool) schemaRow ["IsRowVersion"])
				return false;
			if (!schemaRow.IsNull ("IsExpression") && (bool) schemaRow ["IsExpression"])
				return false;
			if (!schemaRow.IsNull ("IsReadOnly") && (bool) schemaRow ["IsReadOnly"])
				return false;

			return true;
		}
		
		private SqliteParameter CreateParameter (DataRow schemaRow)
		{
			string sourceColumn = (string) schemaRow ["BaseColumnName"];
			string name = String.Format ("@{0}", sourceColumn);
			DbType dbType = (DbType) schemaRow ["ProviderType"];
			int size = (int) schemaRow ["ColumnSize"];

			return new SqliteParameter (name, dbType, size, sourceColumn);
		}

		private SqliteParameter CreateParameter (int parmIndex, DataRow schemaRow)
		{
			string name = String.Format ("@p{0}", parmIndex);
			string sourceColumn = (string) schemaRow ["BaseColumnName"];
			DbType dbType = (DbType) schemaRow ["ProviderType"];
			int size = (int) schemaRow ["ColumnSize"];

			return new SqliteParameter (name, dbType, size, sourceColumn);
		}

		private string GetQuotedString (string value)
		{
			if (value == String.Empty || value == null)
				return value;
			if (String.IsNullOrEmpty (_quotePrefix) && String.IsNullOrEmpty (_quoteSuffix))
				return value;
			return String.Format ("{0}{1}{2}", _quotePrefix, value, _quoteSuffix);
		}

		private void RowUpdatingHandler (object sender, RowUpdatingEventArgs args)
		{
			if (args.Command != null)
				return;
			try {
				switch (args.StatementType) {
				case StatementType.Insert:
					args.Command = GetInsertCommand ();
					break;
				case StatementType.Update:
					args.Command = GetUpdateCommand ();
					break;
				case StatementType.Delete:
					args.Command = GetDeleteCommand ();
					break;
				}
			} catch (Exception e) {
				args.Errors = e;
				args.Status = UpdateStatus.ErrorsOccurred;
			}
		}
	}
}
